Validity Study of the South Oaks Gambling Screen (SOGS) among distinct groups of Brazilian gamblers
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Rev Bras Psiquiatr 2002;24(4):170-6
Validity Study of the South Oaks Gambling Screen
(SOGS) among distinct groups of Brazilian gamblers
Estudo de validade da escala South Oaks Gambling Screen junto a
grupos distintos de jogadores brasileiros
Maria Paula MT Oliveiraa, Maria Teresa Araujo Silvab and Dartiu Xavier da Silveirac
Ambulatory of Pathological Gambling of the Program for Orientation and Attention of Dependent Persons (PROAD), Department of Psychiatry of the Federal
a
University of São Paulo (UNIFESP). São Paulo, SP, Brazil. bDepartment of Experimental Psychology, Institute of Psychology, University of São Paulo. São
Paulo, SP, Brazil. cCoordinator of the Program for Orientation and Attention of Dependent Persons (PROAD), Department of Psychiatry of the Federal
University of São Paulo (UNIFESP). São Paulo, SP, Brazil
Abstract Objective: The main objective of this study was to assess the internal consistency and to perform a factor
analysis of the Brazilian version of the SOGS - South Oaks Gambling Screen - scale, as well as its ability
to discriminate between different profiles of gamblers.
Method: Two hundred and seventeen subjects were enrolled in the study: 46 gamblers under treatment at
the Gamblers Treatment Unit of PROAD - Program for Orientation and Attention of Dependent Persons-
of the Federal University of São Paulo; 96 social gamblers and 75 subjects screened as pathological gamblers
recruited at the local Jockey Club, video poker and bingo clubs.
Results: Differences in the score means of all three groups were statistically significant and were able to
discriminate between social gamblers, pathological gamblers interviewed in a gambling site and the clinical
sample. The internal consistency of the 20-item scale measured by Cronbach’s alpha was 0.9304. Factor
analysis resulted in a three-dimensional solution accounting for 58,6% of the total variance: a first factor
composed mainly by questions related to the consequences of gambling; a second factor encompassing
questions related to the gambling behavior of pathological gamblers; and a third and less expressive factor
involving only two questions, probably a hybrid one of difficult interpretation.
Conclusions: The Brazilian version of the SOGS was a useful screen to discriminate Brazilian pathological
gamblers from social gamblers as well as to differentiate clinical pathological from non-clinical pathological
gamblers, and to identify different levels of severity.
Keywords Pathological gambling. Screening. Scales. Validity.
Resumo Objetivos: O objetivo desse estudo é avaliar a consistência interna e a dimensionalidade da versão da
South Oaks Gambling Screen (SOGS) adaptada para uso em população brasileira e sua capacidade de
discriminar diferentes tipos de jogadores.
Método: O estudo envolveu 217 jogadores – contatados no Jockey Clube de São Paulo, em casas de bingo
e de vídeo pôquer –, sendo que 46 deles haviam procurado tratamento no Ambulatório de Jogo Patológico
do Programa de Orientação e Atendimento a Dependentes da Universidade Federal de São Paulo.Entre
eles 96 eram jogadores sociais e 75 eram classificados como prováveis jogadores patológicos.
Resultados: As diferenças das médias de pontuações das subamostras foram estatisticamente significantes,
discriminando jogadores sociais e jogadores patológicos entrevistados em local de jogo e amostra clínica.
A SOGS, em sua versão integral de 20 itens, apresentou consistência interna medida pelo modelo Alfa de
Cronbach de 0,9304. A análise fatorial da estrutura da escala resultou em uma solução de três dimensões,
respondendo por 58,6% da variabilidade total dos dados na amostra: um primeiro fator constituído
preponderantemente por questões referentes a conseqüências do comportamento de jogar; um segundo
fator reunindo predominantemente questões relativas ao próprio comportamento de jogar dos jogadores
patológicos; e um terceiro fator, menos decisivo no conjunto e composto de apenas duas questões, parecendo
ser um fator híbrido de difícil interpretação.
Conclusões: A versão adaptada para o Brasil da SOGS mostrou-se um instrumento útil para discriminar
Sponsored by the CNPq (process nº 520591/96-8).
Received on 28/11/2000. Reviewed on 5/2 and 9/5/2002. Approved on 16/7/2002.
170Rev Bras Psiquiatr 2002;24(4):170-6 Validity of SOGS
Oliveira MPMT et al.
jogadores brasileiros patológicos de jogadores não-patológicos, como também diferenciou os grupos clínico
e não-clínico de jogadores patológicos, identificando graus distintos de gravidade.
Descritores Jogo de azar. Peneiramento. Escalas. Validade.
Introduction scale was considered as the most appropriate cutoff point to
In the last twenty years, in several places around the world obtain a maximum reduction of both false positives and false
there has been an increasing offer of gambling, including state- negatives. The internal validity of the scale was confirmed
sponsored gambling, such as lotteries, bingo and casinos. The through the assessment of its internal consistency using the
increase in the availability of gambling led some authors to Cronbach’salpha (0.97,pValidity of SOGS Rev Bras Psiquiatr 2002;24(4):170-6
Oliveira MPMT et al.
bling sites: bingo, video-poker and Jockey Club. Twenty-five metric statistic tests, with the SPSS and EPIINFO programs.
questionnaires of probable pathological gamblers for each In order to verify if in a sample two or more variables were
gamble category were collected.19 independent from each other we used the chi-square test.
When data were presented as frequencies of categories, we
Instrument also used the chi-square test to determine the significance of
We used the SOGS – South Oaks Gambling Screen,7 trans- differences between two independent groups. When the stud-
lated into Portuguese and adapted as described bellow. It in- ied variable had a normal distribution in the population from
cluded questions about socio-demographic data, gambling in which the samples were extracted, we used the Student’s t
the prior 12 months, frequency of gambling in the last 30 days test to compare two independent means. When the studied
for each type of gamble and questions about the last 12 months continuous variable had not a normal distribution, non-para-
for other items of the scale. A question about alcohol consump- metric tests were used to compare the independent samples
tion by the gamblers’ parents was added. However, the answers (Kruskal-Wallis). In order to examine the interrelations be-
to this complementary question were not included in the calcu- tween three or more variables we used the logistic regression
lation of the total score, thus assuring its comparability with model as the dependent variable was dichotomic. Significance
other versions of the instrument. The original scale has 20 ques- levels of 0.05 were adopted and the respective degrees of free-
tions to assess gamblers’ behaviors that were kept in the ques- dom (df) were presented.
tionnaire. The cutoff point used was 5, being considered as The Principal Components Analysis (PCA) of the SOGS
probable pathological gamblers those who had a score equal to enables the detection of the number of components (factors
or higher than 5. The other questions added to the scale were of the scale), of the total variance explained of each compo-
not computed in this score. nent and of the factor loadings of each question of the scale.
The number of components provides the quantity of dimen-
Adaptation of the instrument sions of the scale that are independent between them. The
A back translation of the scale was performed in order to total variance explained gives the measure of the capacity of
assure a reliable translation of the scale into Portuguese. The each component to represent the total variability of the data
translated version was administered to 10 patients who sought of our sample. The factor loading is the measure of the inten-
the PROAD due to problems connected to gambling. The ques- sity of the relationship of one variable (question of the scale)
tionnaire has been refined at each application, to facilitate its with one component.
understanding and to improve the quality of the answers. Blank In order to examine the structure of the SOGS used in this
answers, contradictory ones and explicit doubts were taken into study we used the Principal Components Analysis of the
account in this review. The last application, from which was correlation matrix of the questions which compose the scale.
originated the adapted final version, was performed with 20 In order to determine the number of components of the scale
gamblers, being 10 in the Jockey Club and 10 in a bingo club. we used as a criterion the inclusion of the components cor-
In this version, the questionnaire is self-applicable, that is, the responding to the eigenvalues of the matrix that were greater
subject fills in the questionnaire by him/herself, after being than one. After obtaining factor loadings, we used the
properly instructed. The final version of this scale is available varimax rotation method which supplied a new rotated fac-
under request. tor loadings, making easier the interpretation of the factors.
In order to identify which questions more represented by
Procedure which component we used as a criterion with a factor load-
A non-blind trained psychologist applied the questionnaire ing greater than 0.4.
to gamblers who sought attention in the Gamblers Treatment For the inclusion of a question in the model to be sub-
Unit of the PROAD - Federal University of São Paulo during mitted to the Principal Component Analysis (PCA) we used
the first interview. In the field, the application was carried out as a criterion the coefficient of determination (R2) greater
by four trained researchers who went in pairs to the three types than 0.15.
of gambling sites and asked the gambler’s collaboration, ex- In the factor analysis of the instrument correlation matrices
plained the aims of the study and that they should answer the were built to verify the 2x2 correlation of the questions. We
questionnaires by themselves. The questionnaires were filled also calculated the coefficient of determination (R2) of each
in individually, preferentially near to the researchers and then question in relation to all the others in order to determine occa-
were put into an envelope, thus assuring anonymity. Three hun- sional questions with low relevance in the whole. From this
dred and forty-one gamblers were invited to answer from which procedure we built integral matrices which comprised all ques-
139 refused, 21 returned blank questionnaires and 10 of them tions of the scale. The analysis of the principal components
were invalidated due to contradictory answers. The detailed (PCA) was then applied to the matrices of correlation. The fac-
description of the field application was published elsewhere.19 tors composing the instrument were determined selecting those
with an total variance explained greater than 1 (EV>1). We
Statistical analysis used the orthogonal rotation through the varimax method to
The results were analyzed using parametric and non-para- obtain the rotated factor loadings.
172Rev Bras Psiquiatr 2002;24(4):170-6 Validity of SOGS
Oliveira MPMT et al.
Results 6.0. Among social gamblers studied in gambling sites, SOGS
scores ranged from 0 to 13 points, with a mean of 1.95 points,
Sample description standard deviation of 2.27 and median of 1.0. Among gam-
The studied sample was composed by 217 male (82%) and blers classified as probable cases of pathological gamblers who
38 female subjects (18%). The age distribution varied from 16 were interviewed in gambling sites, SOGS scores ranged from
to 76 years and the mean age was 40.3 years with a standard 4 to 22 points, the mean being 9.43 points, the standard devia-
deviation of 11.6. Regarding the marital status, 52 subjects were tion, 4.17, and the mean, 8.0. SOGS scores in the clinical sub-
single (24%), 129 were married (60%) and 31 were divorced sample ranged from 5 to 20 points, with a mean of 14.37, stan-
(14%). As for the religious belief, there were 145 Catholics dard deviation of 3.06 and median of 14. The differences be-
(68%), 11 Protestants (5%), 19 Spiritualists (9%) and 26 claimed tween the means in the three sub-samples were statistically
having no religion (12%). The majority (91%) of studied gam- significant (Kruskal Wallis: x2=153.37; df=2; pValidity of SOGS Rev Bras Psiquiatr 2002;24(4):170-6 Oliveira MPMT et al. from non-clinical populations of pathological gamblers. There- loading higher than 0.5 are displayed first and factor loadings fore, comparing the group composed by the clinical popula- lower than 0.4 were replaced by zero. tion with the group of pathological gamblers studied in gam- From the factor analysis we obtained three factors with total bling sites, we observed significant differences in 11 out of 20 variance explained of 58.6%. The composition of the three fac- questions of the scale: question 1, (x2=14.90, df=1, p
Rev Bras Psiquiatr 2002;24(4):170-6 Validity of SOGS
Oliveira MPMT et al.
vulnerability between pathological gambling and alcohol de- the latter as Diagnostic, whereas the former could be called
pendence among men.22 Adverse consequences or Complications. A third factor, the
In diagnostic procedures that rely on the information sup- least decisive one and composed only by two questions, seems
plied by patients physicians have to tackle with the problem of to be a hybrid one, difficult to be interpreted. It must be high-
its reliability. In order to optimize the reliability of the infor- lighted that screening scales measure psychopathological di-
mation, researchers assess the several symptoms related to dif- mensions not necessarily specific to a certain psychiatric dis-
ferent aspects of a same pathological condition. Therefore, a order. Therefore, from the clinical point of view, certain di-
scale of symptoms tends to be more reliable than the items that mensions may not be clear enough to specify the psychopatho-
compose it if they are positively correlated. In our study, the logical entity they are referred to. This may be a possible
internal consistency of the SOGS as measured by the explanation to obtain this third factor. Other studies involv-
Cronbach’s Alpha was 0.93, indicating that the questions con- ing different populations of gamblers would be needed to
verged to the same construct. Studies using the SOGS in other verify if this kind of grouping of questions is repeated, con-
countries18 suggest that several of the questions of the scale firming our finding of the stability of the factor structure.
may lose their discriminating capability due to transcultural Moreover, studies comparing the discriminating capability of
differences. This phenomenon was not observed in our soci- the SOGS with that of other instruments would be desirable.
ety. As none of the questions had a low correlation with the
others, we may conclude that the integral version of the scale Conclusion
is the one that accounts for the best performance of the instru- The SOGS not only was able to discriminate between patho-
ment in our environment. logical and non-pathological gamblers but also to differentiate
In our study the factor analysis of the scale’s structure re- the group of clinical from the non-clinical pathological gam-
sulted in a three-dimensional solution. From the three evi- blers, identifying different levels of severity. Complementa-
denced factors, one was mainly composed by questions re- rily, we identified eleven items in the scale that have this dis-
lated to the consequences of the gambling behavior, whereas criminating capability. This group of eleven questions could
a second factor was related mainly to the proper behavior of occasionally represent a sub-scale to predict the need of a thera-
gambling in pathological gamblers. Transitorily we may name peutical intervention.
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